Question

All the edges of a cube have the same length. Tony claims that the formula SA = 6s, where s is the length of

Answer 1

Answer:

Here's what I get  

Step-by-step explanation:

a. Net of a cube

Fig. 1 is the net of a cube  

b. Does the formula work?

Tony's formula works if you ignore dimensions.

There are six squares in the net of a cube.

If each side has a unit length s, the total area of the cube is 6s.

c. Will the formula work for any rectangular prism?

No, because a rectangular prism has sides of three different lengths — l, w, and h — as in Fig. 2.

d. Area of a rectangular prism

A rectangular prism has six faces.

A top (T) and a bottom (b) — A = 2×l×w

A left (L) and a right (R)    —   A = 2×l×h

A front (F) and a back (B) —   A = 2×w×h

                                  Total area = 2lw + 2lh + 2wh

If l = 5 m, w = 6 m and h = 8 m,

$\begin{array}{rl}A &=& \text{2 \times 5 m \times 6 m + 2 \times 5 m \times 8 m + 2 \times 6 m \times 8 m}\\&=& \text{60 m}^{2} + \text{80 m}^{2} + \text{96 m}^{2}\\&=& \textbf{236 m}^{2}\\\end{array}$